The aim of the paper is to analyze the prospective production of raw wood with respect to the expected basic tree species composition and assortment structure on an example of long-term
Trang 1JOURNAL OF FOREST SCIENCE, 54, 2008 (7): 314–320
Wood is a natural product of photochemical
as-similation of carbon dioxide, water and solar
en-ergy; its further technological processing into final
products and goods of final utility value is relatively
simple and ecological Therefore the production of
raw wood material considering its regulation has a
great ecological and economic importance in every
country
In the Slovakia considerable attention has been
paid to the issues of wood production and regulation
of its felling Permanent forest monitoring, mainly of
the growing stock in forest stands during continual
renewal of forest management plans is a proof of
that This is also connected with the calculation of
felling possibilities, i.e of it allowable cut according
to counties and for the whole country (Kanka 1985; Greguš 1989; Petráš, Mecko 1999) In addition to these final products of forest management, develop-ment of some methods and materials that were used for their processing needs to be mentioned This cov-ers a spectrum of the methods for monitoring grow-ing stocks in forest stands as presented by Šmelko (2000) including a broad use of domestic yield tables (Halaj et al 1987; Halaj, Petráš 1998), ages of rotation maturity and decennial thinning percents (Halaj et al 1986, 1990) as well as empirical cutting percentages for regeneration timber felling (Greguš
1969) Methodical solutions of this field are relevant
as cited by Herich and Hladík (1993), Herich (1994) and Marušák (1998, 1999) as well
Supported by the Government of the Slovak Republic, Project No 2003 SP 26 028 OC 04 Modification of Utility Properties of Wood Materials and Extension their Using.
Analysis of the production potential of raw wood
in the forests of Slovakia
R Petráš, J Mecko
National Forest Centre – Forest Research Institute Zvolen, Zvolen, Slovakia
ABSTRACT: Production of raw wood material and its regulation has a great ecological and economic importance in
every country The aim of the paper is to analyze the prospective production of raw wood with respect to the expected basic tree species composition and assortment structure on an example of long-term development of selected indicators
of forest condition in Slovakia For this analysis we used data on the area, growing stock and planned decennial timber felling in the forests of Slovakia in 1980, 1996 and 2003 The production potential of forests was evaluated on the basis of the annual perspective allowable cut by 2020, from which the prospective production of assortments was derived using the models of assortment yield tables of tree species The results show that in the forests of Slovakia there is an about half proportion of coniferous and half proportion of broadleaved tree species, very good structure of growing stock as well as its trend in the last years Production of raw wood assortments for industrial processing for the years 2010–2020
is limited by the volume 6.3–6.4 mil m3 About one half of this volume comes from coniferous and the other half from broadleaved tree species For coniferous tree species the proportion of spruce and fir is 87% and for broadleaved tree species the proportion of beech and oak is 80% For coniferous tree species sawmill assortments have a decisive, almost 70% proportion Regarding broadleaved tree species, pulpwood assortments with 47% proportion prevail, although with 11% the highest quality assortments for the production of veneer from beech and oak are also significant
Keywords:production of raw wood; allowable cut; production of raw wood assortments
Trang 2In Germany Polley et al (1996) dealt with these
issues in more detail They derived allowable cuts
by 2020 for the whole country as well as for the
re-spective federal states In former federal states their
prognostic model was derived from the database on
large-scale forest inventory carried out in 1986 to
1990, while for new federal countries the database
of state, military and church forests of former
demo-cratic Germany updated in 1989–1993 was used The
obtained results are very valuable especially from
the aspect of methodology since in one country two
database sources with different contents and data
structure were used for one purpose Other authors,
like Schwarzbauer (1994), Hinssen (1994),
Sii-tonen (1995), Kupka (1995), Hradetzky (1995)
and Nabuurs and Päivinen (1996), also dealt with
the expected model of raw wood production
The aim of this paper is to present how to derive
the prospective production of raw timber, expected
basic composition of tree species and structure of
assortments on an example of forest condition in
Slovakia
MATeRiAlS And MeThodS
The material used in this study comprises data
on forest area, growing stock and planned
decen-nial timber felling in the forest stands of Slovakia
in 1980, 1996 and 2003 The data are arranged into
the sets according to age classes, groups of tree
spe-cies (coniferous, broadleaved) and forest categories
(commercial forests, special-purpose forests and
protective forests) The material was provided by
Lesosprojekt (1980, 1997, 2004) from its own
central data bank on the forests of Slovakia, which
is updated regularly every year using the data on
the forest stand status obtained from the renewal of
forest management plans Data on the area of about
way
For the purpose of the production potential
analy-sis, average decennial cutting percentages DC of
tending and regeneration felling were calculated as
regards the years 1980, 1996 and 2003 pursuant to
the formula:
DC
V
where:
DF – planned decennial cutting according to forest
manage-ment plan (m 3 ),
V – growing stock (m3 ).
The utilization of forest production potential
was evaluated from the annual prospective
allow-able cut AC that was calculated by the year 2020
as follows:
DC%
1,000
where:
DC% – decennial cutting percentage according to formula (1),
V – growing stock (m 3 ).
Cutting percentages from formula (1) were calcu-lated for all sets of stands arranged to age classes, groups of tree species and forest categories In ad-dition, one-year allowable cuts in the interval of the calendar years 2003–2020 were calculated for these
sets Petráš and Mecko (1999) presented the
de-tailed calculation procedure
The prospective production of assortments was derived from prospective allowable cuts by 2020 and from the models of assortment yield tables of tree species (Petráš et al 1996) that give the proportion
of quality and diameter classes of logs in stands with regard to their age and site index According to the external and internal quality of timber assortment tables distinguish 6 quality classes of logs with pre-vailing industrial processing for:
I – sliced decorative veneers for the production of
furniture, special sport and technical needs,
II – peeled veneers, matches, wooden barrels, III – poles, building timber and saw logs that are divided into higher IIIA and lower IIIB quality
class,
V – production of pulp, cellulose and
agglomer-ated boards,
VI – fuel.
To assort calamity wood (snags and windthrows) of coniferous tree species we used the arrangement of the assortment structure by Halaj et al (1990) and Petráš et al (1995) For coniferous tree species the proportion of salvage felling for the years 1986–2002 was about 50–80%, out of which about one half comes from windthrows and the other half from snags In the case of broadleaved tree species salvage felling was only 14–34% From these values we estimated the future trend of salvage felling by 2020, namely for conifers its proportion was estimated at about 60%, and of this one half for windthrows and one half for felling of snags For broadleaved tree species
we estimated the proportion of salvage felling to be approximately 25%, but since no objective data were available, their assorting has not been carried out
ReSulTS And diSCuSSion
For the illustration and examination of long-term development of forests basic data were processed
Trang 3Table 1 presents the development of two basic
pro-duction indicators, namely the area of forest stands
and growing stock in 1980–2003 It is obvious that
while the area of forest stands increased only by 3.6% for the mentioned period, growing stock increased
by 34.4% An extremely high increase of growing
Table 1 Stand area and growing stock in the forests of Slovakia in 1980, 1996 and 2003
1980
1996
2003
Change
1980–2003
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Age classes
Fig 1 Proportion of stand area (thin line) and growing stock
(thick line) of broadleaved tree species in age classes in 1980,
1996 and 2003
0 5 10 15 20 25 30 35 40 45
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Age classes
Fig 2 Planned decennial percents of tending (thin line) and regeneration timber felling (thick line) of broadleaved tree species in age classes in 1980, 1996 and 2003
Trang 4stock, by 50.4%, was recorded for broadleaved tree
species when compared with the year 1980 In
com-parison with the development of growing stocks in
other countries (Spiecker et al 1996) this is not a
surprising fact In Slovakia this increase can mainly be
caused by introducing domestic yield tables (Halaj
et al 1987; Halaj, Petráš 1998) into the practice of
forest management in 1990 in the whole territory of
Slovakia Since 1990 the growing stock in most stands
has been determined using these yield tables For the
observation period, the proportion of broadleaved
tree species increased at the expense of conifers from
57% to 59% and from 47% to 53% when we derived it
from stand area and growing stock, respectively
To evaluate prospective allowable cuts of timber
felling, the time continuity of long-term
develop-ment of stand area, growing stock and intensity
of timber felling is very important As an example
Fig 1 represents the development of the proportion
of stand area and growing stock of broadleaved tree
species in age classes for the years 1980–2003 We
can see that the shift of all curves by 1–2 degrees
higher is not mechanical Changes in the area
dis-tribution of age classes occurred mainly due to the
realization of regeneration felling, including salvage
felling in the stands of lower age classes Dynamic
changes in the distribution of the growing stock to
individual age classes are obvious, since their
in age classes 2–8 the proportions of growing stock
decreased by about 6%, while in age classes 10–12 its increase can be seen
The intensity of timber felling was evaluated ac-cording to decennial cutting percentages calculated from formula (1) Their values for the category of broadleaved commercial forests are illustrated in Fig 2 It is obvious from the data that the highest cutting percentages for tending as well as regen-eration felling were recorded in 1980 In 1996 the cutting percentages of tending felling were lower
by 1–3% when compared with 1980, and for regen-eration felling almost by 12% in some age classes The differences between the years 1996 and 2003 are smaller
Fig 3 represents the development of perspective allowable cuts calculated according to formula (2) The volume of tending felling for the years 2005 to
2020 slightly decreased, in coniferous tree species by
slightly increased, namely in coniferous tree
co-niferous and broadleaved tree species together was
decreased by 20–17% and the proportion of regen-eration felling slightly increased by 80–83% This relatively low proportion of tending felling and high
0
1
2
3
4
5
6
7
3 )
tending felling regeneration felling
Together Broadleaved
Coniferous
Fig 3 Allowable cut of tending and re-generation timber felling of coniferous and broadleaved tree species for the years 2005–2020
Trang 5proportion of regeneration felling as well as almost
the same composition of coniferous and broadleaved
tree species show a very high production potential of
the forests in Slovakia for the following 15 years
From total allowable cuts in 2010–2020 with the
suitable for industrial processing was derived
us-ing the assortment models, namely quality classes
makes about 94% of the total allowable cut From
the remaining volume, approximately 4% represent
quality class VI, i.e fuel wood, and 2% is wood not
suitable even as fuel, i.e waste wood
Fig 4 illustrates volumes of quality classes of
logs I–V together for individual tree species for
the whole Slovakia The highest volume in 2010,
0
250
500
750
1,000
1,250
1,500
1,750
2,000
2,250
2,500
3 )
Coniferous tree species Broadleaved tree species
0
250
500
750
1,000
1,250
1,500
1,750
2,000
2,250
2,500
2,750
3,000
3,250
3 )
Coniferous tree species Broadleaved tree species
Fig 4 Prospective prognosis of the production of quality classes of logs I–V for the years 2010–2020 according to tree species
Fig 5 Prospective prognosis of the production of quality classes of logs for the years 2010–2020
Trang 6tree species reach substantially lower volumes
hornbeam and spruce with fir is expected, while
the volumes of black locust and poplar decrease
ap-proximately the same volume
As Fig 5 documents, in the interval of the years
2010–2020 and in the category of coniferous tree
species we expect the volume of about 2,900 to
dia-meter class The volume of quality classes of logs
same figure illustrates the volumes of quality classes
of logs for broadleaved tree species as well Their total
In quality class IIIA and IIIB there is about 650 to
in quality class I While for coniferous tree species the
total volume of quality classes I–V increases by about
tree species this change will be relatively small
ConCluSionS
To derive the allowable cuts distribution of
grow-ing stock by age classes and intensity of timber
fell-ing is the most important Based on the presented
analysis we can state that the forests of Slovakia have
very suitable tree species composition, structure of
growing stock by age classes as well as the dynamics
of their development in the last years
Production of raw timber assortments for
indus-trial processing is limited by total timber felling For
the years 2010–2020 we expect the felling volume
Approximately one half of this volume is for
conifer-ous tree species and the other half for broadleaved
tree species For coniferous tree species quality
classes I–II account for about 3%, quality class III
for 67% and class V for 30% For broadleaved tree
species quality classes I–II account for about 11%,
quality class III for 42% and class V for 47%
Regard-ing coniferous tree species, spruce with fir account
for the decisive proportion of 87%, while in the
group of broadleaves beech with oak account for
80% It means that saw timber assortments of
qual-ity classes IIIA and IIIB make the decisive, almost
70% proportion of the volume of coniferous tree spe-cies Although in the case of broadleaved tree species
pulp assortments of quality class V prevail, an 11% pro- portion of quality classes I–II, i.e of the highest
qual-ity assortments of beech and oak, is worth mention-ing Though during the derivation of allowable cuts and potential production of the assortments of raw timber several factors were considered, including the relatively high proportion of salvage felling of coniferous tree species, it is difficult to forecast their development more accurately Specific conditions
in the management of forests will be decisive These can be considerably influenced by high salvage fell-ing as well as by the conditions for the realization of mainly tending timber felling Market conditions will
be important as well, as they can significantly affect not only the total volume of raw timber but also the structure of assortments
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Received for publication February 19, 2008 Accepted after corrections May 14, 2008
Corresponding author:
Doc Ing Rudolf Petráš, CSc., Národné lesnícke centrum – Lesnícky výskumný ústav Zvolen, T G Masaryka 22,
960 92 Zvolen, Slovensko
tel.: + 421 455 314 231, fax: + 421 455 314 192, e-mail: rudolf.petras@nlcsk.org
Analýza produkčného potenciálu surového dreva v lesoch Slovenska
ABSTRAKT: Produkcia drevnej suroviny vrátane jej regulácie má v každej krajine veľký ekologický a
hospodár-sky význam Cieľom práce je na príklade dlhodobého vývoja vybraných ukazovateľov stavu lesov Slovenska analyzovať výhľadovú produkciu surového dreva vrátane očakávanej základnej skladby drevín a štruktúry sortimentov Materiál tvoria údaje o výmere, zásobe a plánovanej decenálnej ťažbe dreva v lesoch Slovenska v rokoch 1980, 1996 a 2003 Produkčný potenciál lesov sa posudzoval podľa ročného výhľadového etátu ťažby dreva do roku 2020 Z neho sa podľa modelov sortimentačných rastových tabuliek drevín odvodila výhľadová produkcia sortimentov Výsledky dokazujú, že v lesoch Slovenska je približne polovičné zastúpenie ihličnatých a listnatých drevín, veľmi dobrá štruktúra zásob dreva, ale aj jej vývoj v posledných rokoch Produkcia sortimentov surového dreva na priemyselné spracovanie pre roky 2010–2020 je limitovaná objemom 6,3–6,4 mil m3 Približne polovica z tohto objemu je pre ihličnaté a polovica pre listnaté dreviny
V ihličnatých drevinách má rozhodujúce 87% zastúpenie smrek s jedľou a v listnatých 80% buk s dubom Pri ihličnatých drevinách majú rozhodujúci, takmer 70% podiel piliarske sortimenty Pri listnatých drevinách prevažujú s 47 % vlákninové sortimenty, ale významný je aj 11% podiel najkvalitnejších sortimentov na výrobu dyhy z buka a duba
Kľúčové slová: produkcia surového dreva; etát ťažby dreva; produkcia sortimentov surového dreva